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Virus Resistant Plums
Overview Fruits and vegetables are frequently genetically modified to produce products with a more desirable phenotype. Oftentimes, the genetic modifications are a direct result of a problem observed in a species population. Plums are a good example of this. Plum pox (PPV) affects all stone fruits, especially plums, and the virus is transmitted to the plant by aphids. While the virus causes no harm to humans, it will cause the fruit to become off-tasting and deformed, making the product less desirable to consumers. A new strategy was developed to help combat the virus. Researches have developed plums that have a specialized protein coating that helps to neutralize the plum pox virus before the plant can become infected. Hily, Jean-Michel, et al. "[http://link.springer.com/article/10.1007/s11248-004-8702-3 Stability of gene silencing-based resistance to Plum pox virus in transgenic plum (Prunus domestica L.) under field conditions.]"''Transgenic Research'' 13.5 (2004): 427-436. Plum Pox Plum pox has historically been a European disease, occurring primarily in the Mediterranean and Middle East regions starting around 1915. The disease spread to the US in 1999 and began spreading around North America soon after. http://www.aphis.usda.gov/publications/plant_health/content/printable_version/fs_rev_ppox_08.pdf Unfortunately, once a tree is infected, there is no cure for the disease. Since trees are infected with PPV via insects, entire populations of trees can be infected very easily and the virus can be very devastating to the plum fruits produced by the trees. Once the virus began spreading more rapidly around the world, people began researching a vaccine with the goal of preventing the undersirable impacts on the virus on the plums produced by infected trees. Researchers developed what they called a PPV coat protein that protects the plums from being infected. Development of the PPV Coat Protein Viral coat proteins appear in many plants as a mechanism of preventing any damage that can be caused by viral attacks. Many coat proteins (CP) have been discovered and isolated from plants such as tobacco, alfalfa, cucumber, and potato. Scorza, Ralph, et al. "[http://link.springer.com/article/10.1007/BF00233291 Transgenic plums (Prunus domestica L.) express the plum pox virus coat protein gene]." ''Plant Cell Reports'' 14.1 (1994): 18-22. CP genes have been transferred between plant species in the past with success. Previous research showed success using the PPV-CP from ''Nicotiana ''tobacco plants in apricots to confer resistance to viral invasion. da Câmara Machado, Margit Laimer, et al. "[http://link.springer.com/article/10.1007/BF00231834 Regeneration of transgenic plants of Prunus armeniaca containing the coat protein gene of plum pox virus]." ''Plant Cell Reports'' 11.1 (1992): 25-29. Testing the resistance of plum plants to PPV using CP was done by creating 5 different clones containing the PPV-CP gene. Each variant had different levels of CP expression due to differences in the transformation. Clones C2, C3, and C4 appeared to carry one, two and three copies of the PPV-CP gene respectively. They produced the greatest amount of transcript. Clones C5 and C6 appeared to have two and one inserts respectively with both potentially having rearrangements of the PPV-CP gene. The C5 and C6 clones were the first to show resistance to PPV but the C2, C3, and C4 clones showed the most potential for future use. References